What Causes Bitter Cucumber

cucumber-growing
Image by Joe Quick

By Heather Rhoades

Cucumbers fresh from the garden are a treat, but occasionally, a gardener bites into a homegrown cucumber and thinks “my cucumber is bitter, why?” Understanding what causes bitter cucumber can help to prevent having bitter cucumbers.

Why a Cucumber is Bitter

Cucumbers are part of the Cucurbit family, along with squash and melons. These plants naturally produce chemicals called cucurbitacins, which is very bitter and, in large quantities, can make a person ill. Most of the time, these chemicals are confined to the leaves and stem of the plant, but can work their way into the fruit of the plant in certain conditions causing bitter cucumbers.

What Causes Bitter Cucumber?

Too hot – One of the most common reasons why a cucumber is bitter is due to heat stress. If a plant is stressed due to heat, it may start producing bitter cucumbers.

Uneven watering – Another possibility for what causes bitter cucumber is if a cucumber goes through alternating periods of drought and overwatering, the stress from this can cause the plant to produce bitter fruit.

Temperature fluctuations – If the temperature fluctuates dramatically from one extreme to another over an extended period of time, the plant may start producing bitter cucumbers.

Heredity – Perhaps the most frustrating reason why a cucumber is bitter is simple genetics. There is a recessive trait that can cause a plant to produce bitter fruit from the start. You may plant seeds from the same packet and treat them all the same, only to discover one of the plants produces bitter cucumbers.

My Cucumber is Bitter, How Can I Prevent This?

In order to prevent bitter fruit, you have to address what causes bitter cucumber fruit in the first place.

Always use best practices when it comes to raising your cucumber. Keep cucumbers in an even temperature, which means that you should be planting the cucumber so that it gets the right kind of sun for your climate (sunnier areas in cool climates, morning and afternoon sun only in hotter climates). Water evenly and regularly, especially in times of drought.

Unfortunately, once a cucumber plant starts to produce bitter fruit, it will most likely continue to produce bitter cucumbers. You should remove the plant and start over.

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